Make your app startup as fast as possible to be responsive to user actions is vital. Not only that you risk that your app is being killed by the system, you also risk that the user is not willing to accept slow launch times and will immediatly delete your app right after installation.
After installing Xcode 4.3 I found myself with an ibtool saying that the Xcode directory is not set correctly. As I choose to remove the old installations of Xcode I removed the Developer directory where the ibtool resides too. This worked for me. sudo /usr/bin/xcode-select -switch /Applications/Xcode.app/Contents/Developer/
Convert your @dynamic myPropertyName to #define k_PRE_MyPropertyName @"myPropertyName" and use the define in your code whenever you need use [myClass valueForKey:@"myPropertyName"].
Get a well formated NSString for NSDate differences
I've come accross a "problem" during core data model generation that variables are in the editor are sorted but in your *.h and *.m files in random order. As I just felt in love with automator I found that this is the right place to find a solution to that.